The number and style of class features classes get in Daggerheart is based on balance and what's expected as a class power (from what I've studied). The design team is a little loose with how these are done sometimes (see the Wizard and Sorcerer getting the D&D 5E prestidigitation arcane/divine split feature which could've been a spell instead).
The thaumaturge is inspired by the old-school D&D 2.5 mystic theurge, which was a partial divine and arcane prestige class. Daggerheart has the Hope and Fear mechanics, and I thought it would be unique to have a class that can interact with Fear, especially because in playtesting GMs would not always spend Fear freely (this was during the summer of 2025, before the Witch was designed, so I was happy to see Darrington Press had a similar idea).
If I were to give the thaumaturge a second class feature, it would be something that interacted with Hope on the field. Something where players could trade Hope between each other would be nice, in my opinion. If you want a second class feature, use this and let your table know the creator said it's ok. ;)
Quirk of Fate
With a touch you can shift the winds of fate between souls. While touching two willing allies, you can transfer one Hope from an ally with 3+ Hope to another ally with less than 3 Hope.